Mobility management schemes provide home/host and location mapping for mobile devices (herein mobile nodes) that connect to a network, such as a global information network, e.g., the Internet. The network may be made up of, for example, multiple Ethernet segments and wireless LAN cells. The location of a mobile node within the network may change frequently. For example, a mobile node may move within the network between wireless LAN cells or from a wireless LAN cell to an Ethernet segment. Mobility management schemes allow communication with the mobile node regardless of its location. One such scheme is Mobile IPv6. Support for mobile nodes under Mobile IPv6 is described in Internet Request for Comments (RFC) 3775 entitled “Mobility Support in IPv6” (referred to herein as RFC 3775).
A mobile node (MN) is associated with a home address (HADDR). The HADDR represents a home link/connection point to the network through which the MN can be reached regardless of its current point of attachment to the network. While moving about the network, the MN may also be associated with a care-of address (COA). The COA represents a foreign link/connection point to the network through which the MN may be currently reached directly.
The MN registers its COA with a home agent (HA), a router accessible at the home link of the MN. The HA keeps binding information for the MN that includes the HADDR and the COA of the MN. The HA may intercept incoming packets addressed to the HADDR of the MN and forward the intercepted packets to the current location of the MN using the COA of the MN.
A MN may communicate with one or more correspondent nodes (CN), e.g., other MNs. As with the MN, the location of each CN may change frequently. Mobile IPv6 provides means for managing handover situations where both the MN and a CN with which the MN is communicating are mobile, such as when the MN and/or the CN change LAN cells. As part of the handover procedure, binding signaling is performed.
In RFC 3775, binding signaling includes performing a return routability (RR) procedure and a binding update (BU) procedure. The return routability procedure enables the CN to obtain some reasonable assurance that the MN is in fact addressable at its claimed COA as well as at its HADDR. With this assurance, the CN will accept binding updates from the MN that instruct the CN to direct data to the MN at its claimed COA.
The RFC 3775 return routability procedure involves a home test and a care-of test. During the home test, the MN forwards a packet to its HA, the HA for the MN receives and forwards the packet to the CN at its HADDR, and an HA for the CN receives and forwards the packet to the CN at its COA. The CN then responds to the home test through the same path. During the care-of test, the MN transmits a packet to the HADDR of the CN and the HA for the CN receives and forwards the packet to the CN at its COA. The CN then responds to the care-of test through the same path.
An MN that is able to prove it is reachable at both its HADDR and its COA is authorized to perform the BU procedure. During the BU procedure, the MN transmits a packet containing a message to the HADDR of the CN and the HA for the CN receives and forwards the packet to the CN at its COA. The information in this message updates the address binding state of the CN so that it may send packets directly to the MN's COA.
The combination of signaling for the return routability procedure (or an alternative authorization procedure that proves to the CN that the MN is reachable at both the HADDR and the COA of the MN) and signaling for the binding update procedure are termed “mobility signaling” in this document. Such signaling introduces delays in handoff time.